1. Field of the Invention
This invention relates to a conveyor device for effecting alignment, and more particularly to a conveyor device for effecting alignment conveniently and which may be used for the alignment of the stage of a semiconductor manufacturing apparatus to achieve highly accurate alignment of a mask and a wafer.
2. Description of the Prior Art
The restraining type gas bearing conveyor device heretofore used as a positioning mechanism for a stage effects the positioning of the stage by controlling the gas pressure supplied to a gas supply pad forming a part of the conveyor device to a high or a low level. This method, however, suffers from a problem that the supplied gas pressure need be varied and therefore, when the supplied gas pressure is controlled to a low level, the rigidity of the guide deteriorates and the gas bearing conveyor device becomes weaker in its resistance to disturbance. There is also a problem that the gap between the guide forming a part of the gas bearing conveyor device and the pad is usually as small as about 10 .mu.m and when the degree of tolerance in the operation as a gas bearing conveyor device is taken into consideration, only several .mu.m can be used as the amount of control.